Among the measures which have been suggested to them by the new relations with one another, resulting from the recent changes in their condition, is that of assembling at the Isthmus of Panama a congress, at which each of them should be represented, to deliberate upon objects important to the welfare of all. The Republics of Colombia, of Mexico, and of Central America have already deputed plenipotentiaries to such a meeting, and they have invited the United States to be also represented there by their ministers. The invitation has been accepted, and ministers on the part of the United States will be commissioned to attend at those deliberations, and to take part in them so far as may be compatible with that neutrality from which it is neither our intention nor the desire of the other American States that we should depart. The commissioners under the seventh article of the treaty of Ghent have so nearly completed their arduous labors that, by the report recently received from the agent on the part of the United States, there is reason to expect that the commission will be closed at their next session, appointed for the 22d of May of the ensuing year. The other commission, appointed to ascertain the indemnities due for slaves carried away from the United States after the close of the late war, have met with some difficulty, which has delayed their progress in the inquiry. A reference has been made to the British Government on the subject, which, it may be hoped, will tend to hasten the decision of the commissioners, or serve as a substitute for it.